Disease_Mapped_To_Gene Spinal Muscular Atrophy Type 3 Spinal Muscular Atrophy III Juvenile Spinal Muscular Atrophy Spinal Muscular Atrophy Type 3 Disease or Syndrome Cellosaurus Spinal Muscular Atrophy Type 3 Kugelberg-Welander Disease A rare, autosomal recessive inherited disorder caused by mutations in the SMN1 gene. It is characterized by progressive degeneration and loss of the anterior horn cells in the spinal cord and brain stem. It is manifested with hypotonia and muscle weakness, usually in late childhood or adolescence. Affected individuals can stand and walk but walking and climbing stairs becomes progressively difficult. C118847 Kugelberg-Welander Syndrome C0152109 SMN1 Gene Cellosaurus Disease Terminology Spinal Muscular Atrophy